FORS is the visual and near UV FOcal Reducer and low dispersion Spectrograph for the Very Large Telescope (VLT) of the European Southern Observatory (ESO). Two versions of FORS have been built, upgraded and moved to the Cassegrain foci of different telescopes in the past years. FORS is designed as an all-dioptric instrument for the wavelength range from 330 nm to 1100 nm and provides an image scale of 0".25/pixel (or 0".125/pixel with the high resolution collimator) in the standard readout mode (2x2 binning). FORS1 is mounted on UT2 (Kueyen) and equipped with a new mosaic of two 2k x 4k E2V CCDs (with 15 μm pixels) optimised for the blue range (<600 nm) while FORS2 is installed on UT1 (Antu) and optimised for the red with a very low level of fringes thanks to a mosaic of two 2k x 4k MIT CCDs (with 15 μm pixels). The geometries of both FORS1 and FORS2 detector systems are very similar: in both cases the detectors are flat and the bottom detector is rotated by 0.08 degrees and shifted by about 30 μm with respect to the upper "master" detector. The gaps between the two detectors are about 480 μm. FORS1 has a polarimetric capability while FORS2 allows multi-object spectroscopy with exchangable masks (MXU) and has a high time resolution mode